A node is a term used in digital communications and networking to denote a point in a network at which lines intersect or branch, a device attached to a network, or a terminal or other point in a computer network where messages can be transmitted, received or forwarded. A node can be any device connected to a computer network. Nodes can be computers, personal digital assistants (PDAs), cell phones, switches, routers or various other networked devices. In the case of a wireless network, the nodes use transceivers (receivers and transmitters) operating at microwave frequencies, e.g., 2.4 GHz ISM band and the like.
A successful transmission of a message(s) between wireless nodes having predefined output power is generally determined by the noise level at the receiving node, e.g., destination node. A lower noise level at the receiving node has the same effect as increasing the sensitivity of the receiving node and/or increasing the transmit power from a transmitting node, e.g., origination node, in communications with the receiving node. The popularity of digital wireless communications, e.g., Wi-Fi, BLUETOOTH® (a registered trademark of Bluetooth SIG, Inc., 500 108th Avenue NE, Suite 250, Bellevue WASHINGTON 98004), ZIGBEE® (a registered trademark of ZigBee Alliance CORPORATION CALIFORNIA, 2400 Camino Ramon, Suite 375, San Ramon, Calif. 94583), etc., has created much interference, for example but not limited to, in the crowded 2.4 GHz ISM band. This interference in effect increases the noise floor and degrades reliable reception by the receiving node.
Referring to FIG. 1, depicted is a traditional wireless network that uses one channel (frequency) to communicate between wireless nodes, i.e., all nodes talk to one another on the same channel. In this example, channel 15 is used for communications between wireless nodes. As the network grows in size (area and number of nodes), the noise level increases or decreases for each receiving node depending on its location and the interference that it is subjected to by interference sources, e.g., WiFi, Bluetooth, etc., transmitting on the same channel. It is desirable to find a channel (frequency) that has the least amount of interference and noise so that receiving (destination) nodes perform optimally. It is highly unlikely that there is a single channel (frequency) that is the optimum for all nodes communicating in a wireless network.